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Advanced Windows PowerShell Scripting Video Training

Advanced Windows PowerShell Scripting Video Training

Tuesday, January 3, 2017

Using functions with PowerShell Background Jobs Part 1 of 2

Happy New Year everyone!
I am spending my New Years’ day working on some code that I’ve been
putting off while the family has been in town.
Something about shoveling sunshine as opposed to shoveling snow. I’m working on expanding some Azure code that
I have developed and I’m looking at ways to further modularize the code. Since I use Background jobs with script
blocks to speed the processes that I am running, I’m looking at using the InitializationScript parameter of Start-Job.

The InitializationScript
parameter allows you to run code before the ScriptBlock parameter runs.
When you include functions inside of it, you are able to place those
functions in the same memory that the ScriptBlock
will execute in. Let’s take a look at
our code to set this up.

First we create a variable that will hold our function that
we will call from the background job.

$JobFunctions = {

FunctionBeep

{

Param ($Tone)

[console]::beep($Tone,200)

}

}

In this case, we are going to make the console beep. We are also going to pass the value for the
tone of the beep to the parameter $Tone.

Next we will set up a splat for a few of the parameters of Start-Job. Notice that we are setting
the value for –InitializationScript to
be the $JobFunctions that we created
above. Also, we need to pass a value to
what will be our script block. That
value is 300.

$JobSplat = @{

Name = "Test1"

InitializationScript = $JobFunctions

ArgumentList = 300

}

Now we can run our background job.

Start-Job@JobSplat-ScriptBlock {

Param($Value)

Beep–Tone $Value

}

First off we call our splat and then we call our script
block. We need to pass the value of 300
to the script block so we created a parameter called $Value. In other words $Value
= 300. Next we call the function that we
sent to the initialization script. The
function name is Beep it has a
parameter called –Tone. We provide it the value of 300 that is
contained in $Value. Once this runs, you will hear a beep.